Cleanroom HVAC

air changes · heat recovery · FFUs · ISO 14644

A clean zone may replace its air several hundred times an hour, against a handful in an office. That airflow, and the reheat that goes with it, makes HVAC the largest non-tool load in a fab.

Bar chart of air changes per hour by cleanliness class: ISO 5 (Class 100) 240 to 480, ISO 6 150 to 240, ISO 7 60 to 90, ISO 8 5 to 48, compared with about 4 to 6 in an office building. Below, four places where the electric swap happens: makeup air preheat by heat pump; reheat by heat-recovery chillers; fans and fan filter units with EC motors, variable-speed drives and setback; and chilled water with warmer loops and free cooling. AIR CHANGES PER HOUR BY CLEANLINESS CLASS ISO 5 (Class 100) 240-480 ISO 6 (Class 1,000) 150-240 ISO 7 (Class 10,000) 60-90 ISO 8 (Class 100,000) 5-48 Office building ~4-6 WHERE THE ELECTRIC SWAP HAPPENS Makeup air heat pump preheat Reheat heat-recovery chillers Fans, FFUs EC motors, VFD, setback Chilled water warmer loops, free cooling
ISO 5 air changes
240-480 per hour
Standard
ISO 14644
HVAC share of cleanroom power
Often 50%+
Companies tracked
17, 4 Chinese
Hub
Industry

Finding

Cleanrooms already run on electric fans and chillers; the electrification step is replacing gas boilers for makeup-air heating and reheat with heat recovered from the plant's own cooling loads

Fabs reject enormous heat through process cooling water and chillers while burning gas to heat outdoor makeup air and to reheat air after dehumidification. Heat-recovery chillers and water-to-water heat pumps move that rejected heat into the hot-water loop, which can take boilers out of service. Fan filter units with EC motors and demand-based airflow cut the largest electrical load.

Demand-controlled airflow, lowering air changes when particle counters show a clean zone is well inside its ISO 14644 class, typically saves up to about 25% of HVAC energy without losing classification. Warmer chilled-water loops let chillers run more efficiently and use more free cooling; separate low-temperature loops serve only the dehumidification coils that need them.

The same playbook applies to battery dry rooms, where dew points near -40 °C or lower make desiccant regeneration a large heat load, and to pharma suites under GMP. The obstacles are validation and design: any change must be re-qualified against ISO class and product yield, and heat-recovery systems need custom engineering. In Texas, the playbook applies to Samsung's Taylor fab and TI's Sherman fabs.

Components

Electrified HVAC components

Each component either removes a combustion heat source or cuts fan and chiller energy.

Cleanroom HVAC components
ComponentWhat it doesElectrification gainWatch-outs
Heat-recovery chillers and heat pumpsLift waste heat from process cooling to hot-water loopsReplace gas boilers for reheat and makeup airNeed simultaneous heating and cooling demand
Makeup air unitsCondition outdoor air that replaces exhaustHeat-pump coils instead of steam or gasLargest heating load in cold climates
Fan filter units (FFUs)HEPA or ULPA filtered recirculationEC motors, variable speed, night setbackThousands of units per fab; controls matter
Demand-controlled airflowSets air changes from particle countsUp to about 25% HVAC savingsMust hold ISO class; requires validation
Energy recovery (run-around coils, heat pipes)Pre-conditions supply air from exhaustCuts fresh-air loadWheels are avoided where exhaust is toxic
Chilled water plantRemoves tool and air heatWarmer loops, free cooling, VFD chillersSeparate loop for dehumidification

Suppliers

Equipment makers and cleanroom builders

Chiller and heat pump makers, filter makers, and the design-build contractors that assemble fab cleanrooms. Active companies first, then pilots, research groups and companies that exited.

Chillers, heat pumps and air handling
CompanyProductsHQTechnologyStatus
CarrierChillers and air handlersUSCentrifugal and screw chillersactive
DaikinChillers, air handlers, heat pumpsJapanChillers and heat pumpsactive
GreeChillers and heat pumpsChinaCentrifugal chillers and heat pumpsactive
HaierChillers and heat pumpsChinaMagnetic-bearing chillers and heat pumpsactive
Johnson Controls (York)Chillers, air handlers, controlsUSCentrifugal chillersactive
MideaChillers and heat pumpsChinaCentrifugal chillers and heat pumpsactive
Trane TechnologiesChillers, heat-recovery chillers, controlsUSCentrifugal and screw chillers; heat-recovery chillersactive
Filtration and fan filter units
CompanyProductsHQTechnologyStatus
AAF InternationalHEPA and ULPA filtersUSFiltrationactive: Daikin subsidiary
CamfilHEPA and ULPA filters, fan filter unitsSwedenFiltrationactive
Cleanroom design-build contractors
CompanyProductsHQTechnologyStatus
ActerFab cleanroom and MEP contractorTaiwanCleanroom systemsactive
China Electronics System Technology (CEC)Fab cleanroom engineeringChinaCleanroom systemsactive
ExyteCleanroom and fab design-buildGermanyEPC for fabs and battery dry roomsactive
L&K EngineeringFab cleanroom and MEP contractorTaiwanCleanroom systemsactive
Sanki EngineeringCleanroom HVAC contractorJapanCleanroom systemsactive
ShinryoCleanroom HVAC contractorJapanCleanroom systemsactive
TaikishaCleanroom HVAC contractorJapanCleanroom systemsactive
United Integrated ServicesFab cleanroom and MEP contractorTaiwanCleanroom systemsactive

Sources

Sources and scope

Scope
Electrified Cleanroom HVAC
Sources
ISO 14644-1; IEST-RP-CC012; LBNL cleanroom energy studies; supplier disclosures
Updated
October 2026